• Title/Summary/Keyword: Data transfer

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Design and Implementation of Transfer Buffer Sharing Technique for Efficient Massive Data Transfer

  • Cho, Dae-Soo
    • Journal of information and communication convergence engineering
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    • v.6 no.3
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    • pp.327-330
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    • 2008
  • It is required that a server which communicates with various client simultaneously should have an efficient data transfer model. In Windows$^{(R)}$ environment, the server was generally developed based on IOCP model. Developing the IOCP model, the server generally has one data transfer buffer per client. If the server divides a larger data than the transfer buffer into several fragments, there used to be a problem in sending it to a client, because there is a conflict in a data transfer buffer. That is, CPU requests one data-fragment transfer, then it will request the next data-fragment transfer successively before completing the previous request, owing to the property of overlapped IO model. In this paper, we proposed the transfer buffer sharing technique to solve the conflicting problem. The experimental result shows that the performance of data transfer was enhanced by 39% maximally.

Reduction of the Wet Surface Heat Transfer Coefficients from Experimental Data

  • Kim, Nae-Hyun;Sim, Yong-Sub
    • International Journal of Air-Conditioning and Refrigeration
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    • v.12 no.1
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    • pp.37-49
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    • 2004
  • Four different data reduction methods for the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two heat and mass transfer models and two fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the reduced heat transfer coefficients revealed that the single potential heat and mass transfer model yielded the humidity-independent heat transfer coefficients. Two fin efficiency models-enthalpy model and humidity model-yielded approximately the same fin efficiencies, and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

Design of Variable Data Transfer Rate Asymmetric TDD System Using Turbo Decoder with Double Buffer Controller (이중 버퍼 제어기 구조의 터보 복호기를 사용한 전송률 가변 비대칭 TDD 시스템 설계)

  • Park, Byeung-Kwan;Kim, Mi-Rae;Kim, Hyo-Jong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.2
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    • pp.161-168
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    • 2019
  • This paper proposes a variable data transfer asymmetric TDD(Time Division Duplex) system for small UAV(Unmanned Aerial Vehicle) data link system. In the proposed method, a turbo decoder with a double buffer controller is proposed to apply turbo decoder with long decoding time to asymmetric TDD system. The proposed method achieves variable data transfer rate and maximum data transfer rate. The advantage of the proposed method is demonstrated by its data transfer rate. The measured data transfer rate is more than 1.8 times than that of symmetric TDD system. In addition, PER(Packet Error Rate) performance is the same and data transfer rate is variable.

A study on the Analogy between Heat Transfer and Mass Transfer (열전달과 물질전달의 유사성에 관한 연구)

  • 유성연;노종광;정문기
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.10
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    • pp.2624-2633
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    • 1993
  • Mass transfer experiment by naphthalene sublimation method has great advantages in measurement of local transfer coefficients in the region of a three dimensional flow or for a model of complex geometry, which is considered to be very difficult with conventional heat transfer measurements. Mass transfer data obtained by naphthalene sublimation technique are converted to the heat transfer data through heat/mass transfer analogy. This analogy is valid for a simple or laminar flow, but new insight is needed when applying to a turbulent flow or complex flow such as separation, reattachment and recirculation, The purpose of this research is to investigate how geometries and flow conditions incorporate heat/mass transfer analogy. Mass transfer experiments are performed using naphthalene sublimation technique for a flat plate, a circular cylinder, and rectangular cylinders. And mass transfer data are compared with earlier heat transfer measurements for the same geometries. Usefulness of analogy relation between heat and mass transfer is examined with these results.

Comparison of Java Virtual Machine and x86 Processor in Data Transfer Viewpoint (자료 이동 측면에서 자바가상기계와 x86 프로세서의 비교)

  • Yang, Hee-Jae
    • Proceedings of the IEEK Conference
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    • 2005.11a
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    • pp.1225-1228
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    • 2005
  • This paper compares the differences between Java virtual machine and x86 processor in data transfer viewpoint. Memory models of JVM and x86 are analyzed and the data transfer paths are identified. As all operations must be performed to the values on operand stack, a great many data transfer operation is unavoidable in JVM. We also lists the number of data transfer operations necessary for executing some typical high-level language statements including assignment, arithmetic, conditional, and iterative statements.

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Heat Transfer Correlations for Air-Water Two-Phase Flow of Different Flow Patterns In a Horizontal Pipe

  • Kim, Dongwoo
    • Journal of Mechanical Science and Technology
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    • v.15 no.12
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    • pp.1711-1727
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    • 2001
  • Heat transfer coefficient were measured and new correlations were developed for two-phase heat transfer in a horizontal pipe for different patterns. Flow patterns were observed in a transparent circular pipe (2.54 cm I. D. and L/D=96) using an air/water mixture. Visual identification of the flow patterns was supplemented with photographic data and the results were plotted on the flow regime map proposed by Taitel and Dukler and agreed quite well with each other. A two-phase heat transfer experimental setup was built for this study and a total of 150 two-phase heat transfer data with different flow patterns were obtained under a uniform wall heat flux boundary condition. For these data, the superficial Reynolds number ranged from 640 to 35,500 for the liquid and from 540 to 21,200 for the gas. Our previously developed robust two-phase heat transfer correlation for a vertical pipe with modified constants predicted the horizontal pipe air-water heat transfer experimental data with good accuracy. Overall the proposed correlations predicted the data with a mean deviation of 1.0% and an rms deviation of 12%.

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Data Reduction on the Air-side Heat Transfer Coefficients of Heat Exchangers under Dehumidifying Conditions (제습이 수반된 공조용 증발기 습표면의 열전달계수 데이터 리덕션)

  • Kim, Nae-Hyun;Oh, Wang-Kyu;Cho, Jin-Pyo;Park, Hwan-Young;Yoon, Baek
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.1
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    • pp.73-85
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    • 2003
  • Four different methods of reducing the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two different heat and mass transfer models and two different fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the data with the reduction methods revealed that the single potential heat and mass transfer model yielded the humidity independent heat transfer coefficients. Two different fin efficiency models - enthalpy model and humidity model - yielded approximately the same fin efficiencies and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

Estimating Station Transfer Trips of Seoul Metropolitan Urban Railway Stations -Using Transportation Card Data - (수도권 도시철도 역사환승량 추정방안 -교통카드자료를 활용하여 -)

  • Lee, Mee-Young
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.38 no.5
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    • pp.693-701
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    • 2018
  • Transfer types at the Seoul Metropolitan Urban Railway Stations can be classified into transfer between lines and station transfer. Station transfer is defined as occurring when either 1) the operating line that operates the tag-in card-reader and that operating the first train boarded by the passenger are different; or 2) the line operating the final alighted train and that operating the tag-out card-reader are different. In existing research, transportation card data is used to estimate transfer volume between lines, but excludes station transfer volume which leads to underestimation of volume through transfer passages. This research applies transportation card data to a method for station transfer volume estimation. To achieve this, the passenger path choice model is made appropriate for station transfer estimation using a modified big-node based network construction and data structure method. Case study analysis is performed using about 8 million daily data inputs from the metropolitan urban railway.

Experiments on Single Phase Cooling Heat Transfer and Pressure Drop Characteristics in Microfin Tubes (마이크로휜관 내 단상 냉각 유동 열전달 및 압력 강하 특성에 관한 실험적 연구)

  • 이규정;한동혁
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.3
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    • pp.231-239
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    • 2002
  • Experiments on the single phase cooling heat transfer and pressure drop with microfin tubes were performed using water as a test fluid. Experimental data were obtained in the range of Reynolds number 3000 ~40000 and Prandtl number 4-6. The data of microfin tubes presented the characteristics of rough surface tube in pressure drop and heat transfer Experimental data were compared with the heat transfer and friction factor correlations of smooth tubes. Heat transfer enhancements of microfin tubes were lower than pressure drop penalty factors. The helix angle is more significant parameter in both of the pressure drop and heat transfer than the relative roughness. The correlations of Nusselt number and friction factor were suggested for the tested microfin tubes. Maximum deviations between correlations and experimental data were within $\pm15$% for Nusselt number and $\pm10$% for friction factor.